New information from climate sciences and paleoecology increasingly challenges our ability to grasp dynamic nature. Key concepts for restoration include regular natural (without human influence) climate oscillating at multiple and nested temporal scales, including interannual, decadal, century, millennial, and multimillennial scales. In addition, transitions between climate phases often occur abruptly, and vegetation responds to climate change. Repetitive climate changes at each scale exert significant recurring evolutionary and ecological forces on vegetation, and species have evolved mechanisms to adapt to ongoing environmental change. These include changes in population size, abundance, and productivity; population migration; colonization; and, when adaptation fails, extirpation. Plant communities exist as transient assemblages as species move individually through time and space following favorable climates and environments.
Such conclusions suggest a rethinking of concepts of sustainability and restoration targets. Rather than restoring historical, “pre-human-disturbance” conditions, we may better help species persist into the future by realigning populations with current and future anticipated conditions, and providing options to cope with uncertain futures and certain high variability. The capacity for populations to grow, decline, migrate, and colonize has determined species survival under past conditions of rapid change. Many situations thwart this capacity at present, including fragmentation, urbanization and development, static land-use policies (including conservation measures such as reserves, easements, etc.), and even rigid conservation philosophies that hold species hostage to specific locations and conditions. Understanding that species have coped with change in the past suggests that restoration sciences have opportunities to assist species cope with the dynamics of the current world.